Computer-assisted support method for projecting an electric line system

ABSTRACT

The topology of a bus or network electric line system which is used to provide a plurality of electric consumers with low voltage from a feed block, is inputted into a computer. For several feed points, a measuring value is determined for the electric line system on the basis of at least one technical criterium and is transmitted to a user as a function of the feed point. It is assumed that the feed block is connected to the electric line system at the respective feed point.

[0001] The present invention relates to computer-aided method forconfiguration of a cable system, via which at least two electrical loadsare intended to be capable of being supplied with low voltage from atleast one supply module,

[0002] with a topology of the cable system being entered in a computer,

[0003] with the cable system having a single section, corresponding tothe topology, per load, via which only this load is intended to becapable of being supplied with electrical power,

[0004] with the cable system having connecting sections, correspondingto the topology, via which the single sections are intended to beconnected to one another and via which it is intended to be possible tosupply in each case at least two of the loads with electrical power.

[0005] In the industrial systems, in particular machines and machinesystems, a large number of electrical low-voltage loads must be suppliedwith electrical power. The loads are often, but not necessarily,single-phase or three-phase AC voltage motors. A 500 V DC voltage, forexample, supply is also known.

[0006] In the past, power was distributed to the loads in switchgearcabinets in which the feed module for the loads was also arranged.Separate cables were routed from the switchgear cabinet to theindividual loads. A cable system thus had a star-like topology. On thebasis of this topology, namely with a separate cable for each load, itwas relatively simple to design the cables. This work could be done evenby electricians using comparatively simple tables.

[0007] Recently, the electrical loads have been connected to an evergreater extent to the feed module via cable systems similar to busses ornetworks. A bus section of the cable system thus originates from thefeed module, via which a network—which possibly may even have furtherbranches—is passed to the individual loads. The bus section carries allthe current for the connected loads. Further sections branch off to theindividual loads, and these are referred to in the following text assingle or end sections, which carry the current for only this singleload.

[0008] The PCT application “Computer-aided test procedure for a cablesystem” (internal file reference 2000 P 03188 WO, priority date Mar. 20,2000, priority file reference 100 13 521.8), which was submitted on thesame date as the present application, describes a test procedure for abus-like or network-like cable system, by means of which it is possibleto check that the design of the cable system is adequate, and by meansof which this cable system may even possibly be designed automatically.However, the topology of the cable system as such is not changed.

[0009] In the method described above, it is possible for the feed moduleto be arranged poorly by the user. This leads to disadvantages duringoperation of the cable system and, in the extreme, even to thepossibility of the cable system no longer being adequately designed orno longer being correctly configurable.

[0010] The object of the present invention is to specify a method bymeans of which the topology of a cable system can also be assessed.

[0011] The object is achieved,

[0012] in that the computer determines a number of feed points at whichthe feed module is intended to be connected to the cable system,

[0013] in that the computer determines a value measure for the cablesystem for each feed point on the basis of at least one technicalcriterion, and

[0014] in that the value measure is output to a user as a function ofthe feed point.

[0015] This is because it is simple for the user to see where good feedpoints for the connection of the feed module are located.

[0016] If the cable system is represented graphically by the computer bymeans of an output device, the value measures are likewise output by thecomputer by means of the output device, and the respective valuemeasures are associated in terms of their positions with thecorresponding feed points in the output, the user can see good feedpoints particularly easily.

[0017] The choice of a particularly good feed point is especially simpleif the computer determines an optimum value measure and the optimumvalue measure is emphasized visually in the output.

[0018] A final feed point is defined once the value measure has beenoutput as a function of the feed point. The final feed point may in thiscase either be defined automatically by the computer or else may bepredetermined by the user for the computer. In the latter case, thepredetermination process is particularly convenient if the computerproposes to the user one of the feed points as a final feed point, andthe computer adopts this feed point as the final feed point if the userenters a confirmation for it.

[0019] The sections of the cable system may, for example, be designed onthe basis of at least one design criterion, with the value measure beingdetermined on the basis of the design.

[0020] If the value measure is determined on the basis of the sum of thesection lengths weighted by the cross section of the cable cores in thesections, this results in the minimum use of materials when choosing anoptimum or virtually optimum feed point. However, other technicalcriteria are also feasible. For example, the value measure may becomegreater the less the maximum voltage drop or the more uniform thecurrent distribution.

[0021] If the cross sections of the cable cores are limited to a maximumcross section, and feed points are marked as not being permissible ifthe design criterion is not satisfied during connection of the feedmodule to these feed points, even for the maximum sizes of the sections,unacceptable feed points can be immediately identified as such in asimple manner.

[0022] If immediately adjacent feed points are separated from oneanother by one grid unit, which is predetermined by the user for thecomputer before determining the value measures, the accuracy fordetermining the value measures can be defined in advance.

[0023] If the grid size is an integer multiple of a basic grid and thefinal feed point is located on the basic grid, this ensures that thefinal feed point can be located on one of the feed points.

[0024] Good feed points can be found even more reliably if at least onefeed point is arranged in each connecting section, independently of thegrid size.

[0025] If at most a predetermined number of feed points are arranged ineach connecting section independently of the grid size, the requiredcomputation time is kept within limits, despite the sections possiblybeing long.

[0026] If the user predetermines for the computer the part of the cablesystem in which the feed points are intended to be arranged, it ispossible, for example in a first step, to predetermine a relativelycoarse grid size and then to select the area in which the value measureassumes high values, and finally to carry out a further value measuredetermination process using a finer grid size, and possibly even aconsiderably finer grid size.

[0027] If the user predetermines the technical criterion for thecomputer, the method operates in a particularly flexible manner.

[0028] If two cable systems are entered in the computer at the same timeand have at least the feed module in common, and the computer determinesa specific value measure for each of the cable systems, the method canbe used in a particularly versatile manner. This is because, inpractice, there is generally at least one actual main cable system andtwo auxiliary cable systems, one of which can be switched (as a resultof an emergency off function), and the other cannot be switched.

[0029] Within the two auxiliary cable systems, it is possible for thecable systems also to have at least one common load. In the relationshipbetween the main cable system and the auxiliary cable systems,situations often arise in which at least one of the loads on the maincable system is preceded by a switching and protection module, and theswitching and protection module is a load on an auxiliary cable system.

[0030] The main cable system is generally operated with a single-phaseAC voltage of, for example, 230 Volts, or a three-phase AC voltage of,for example, 400 Volts. The auxiliary cable systems are generallyoperated either with a DC voltage of, for example, 24 Volts or with asingle-phase AC voltage of, for example, 230 Volts. These situationsmay, of course, possibly also be taken into account in the design of thecable systems and in the determination of the value measure.

[0031] Further advantages and details can be found in the followingdescription of an exemplary embodiment in conjunction with the drawings.In this case, illustrated in outline form:

[0032]FIGS. 1 and 2 show examples of a circuit arrangement,

[0033]FIG. 3 shows a computer layout,

[0034]FIGS. 4 and 5 show a flowchart and

[0035]FIG. 6 shows a modification of FIG. 4.

[0036] As is shown in FIG. 1 (by way of example) five main loads 1 to 5are intended to be supplied with electrical power from at least one—andhere this is precise—feed module 6. Each of the main loads 1 to 5 ispreceded by a switching and protection module 7 to 11. The loads 1 to 5are generally, but not necessarily, motors. The switching and protectionmodules 7 to 11 are generally in the form of a contactor, with a circuitbreaker connected upstream of it.

[0037] A main cable system is provided in order to supply the main loads1 to 5 with electrical power. The main loads 1 to 5 are fed with a mainlow voltage via this main cable system. The main low voltage is avoltage of less than 1 kV, for example a three-phase AC voltage with arated voltage of, for example, 400 Volts. In this case, the main cablesystem typically has five cores (three phases, a neutral conductor andground).

[0038] As is shown in FIG. 1, the main low-voltage system has a main bussection 12, main connecting sections 13 to 17 and main end sections 18to 27. As can be seen, the switching and protection modules 7 to 11 arein this case arranged upstream of the main loads 1 to 5.

[0039] The switching and protection modules 7 to 11 are auxiliary loads,which are supplied with electrical power via auxiliary cable systems. Ascan be seen from FIG. 2, the auxiliary cable systems have the same basicstructure as the main cable system. All that should be noted in additionis that the switching and protection module 7 is not supplied withelectrical power via these two auxiliary cable systems, but in someother way. Furthermore—so to speak by way of replacement—othercomponents 28, 29 which are not included in the main cable system areconnected to one or both of the auxiliary cable systems. The othercomponents 28, 29 may, for example, be actuators or sensors. Theauxiliary loads 8 to 11, 28, 29 may also be connected to one or to bothof the auxiliary cable systems.

[0040] The auxiliary cable systems generally carry a lower voltage thanthe main cable system. Typical voltage values are single-phase ACvoltage of, for example, 230 Volts, or a DC voltage of, for example, 24Volts. In both cases, the auxiliary cable systems may have two cores.

[0041] The cable systems thus have a common feed module 6. Furthermore,the auxiliary cable systems have common loads 8, 10, 29, as shown inFIG. 2. The loads 8 to 11 on the auxiliary cable systems are alsoswitching and protection modules 8 to 11 in the main cable system, as isillustrated in FIG. 1.

[0042] The method according to the invention (configuration tool 37)runs under program control of a computer, for example a PC. As is shownin FIG. 3, this computer has the normal components. These are a computercore 30, input devices 31, 32 (typically a keyboard 31 and a mouse 32),output devices 33, 34 (typically a monitor 33 and a printer 34) and,possibly, an interface 35 to a computer network 36, for example to theInternet.

[0043] When a program 37 is run, which includes the method according tothe invention, the computer communicates with a user 38. In this case,it accesses, inter alia, a file 39 which, for example, is an ASCII file.This contains a topology for the cable systems and specifications forthe sections 12 to 27 of the cable systems, as well as specificationsfor the elements 1 to 11, 28, 29 and can be both read from and writtento.

[0044] The method according to the invention will be described in thefollowing text in conjunction with FIGS. 4 and 5 on the basis of themain cable system. However, it can also be used analogously for theauxiliary cable systems.

[0045] As is shown in FIG. 4, during the running of the program 37,topologies of the cable systems are first of all entered in a step 51and are displayed graphically on the monitor 33—possibly individually,in different windows or superimposed. The loads 1 to 5, the switchingand protection modules 7 to 11 and the further loads 28, 29 are thenspecified in a step 52. The feed module 6 is also specified in the step52. The main and auxiliary loads 1 to 5, 7 to 11, 28, 29 and the feedmodule 6 are predetermined, and this implicitly defines the operatingvoltages with which the cable systems are intended to be operated inpractice, that is to say the voltages with which they can be assumed tobe operated for the purposes of the method.

[0046] A basic grid and a grid size are then entered interactively in astep 53. The grid size must in this case be an integer multiple of thebasic grid. Finally, a step 54 interactively asks whether the computerwill define a final feed point 40 automatically.

[0047] The computer now determines feed points 40 in accordance with astep 55. Immediately adjacent feed points 40 are in this case generallyseparated from one another by one grid unit. However, if it were to befound on the basis of the grid size that no single feed point 40 werearranged in one of the connecting sections 13 to 17, a feed point 40would exceptionally also be arranged in this section, with less than onegrid unit spacing. Furthermore, there are not less than a predeterminednumber (for example ten) of feed points 40 in each connecting section 13to 17.

[0048] In a step 56, the computer now determines a value measure for thecable system for each of the feed points 40, on the basis of a technicalcriterion. This is based on the assumption that the feed module 6 is ineach case connected to the cable system at the respective feed point 40.During this process—and this is described in detail in the patentapplication mentioned above entitled “Computer-aided test procedure fora cable system”—the sections 12 to 27 of the cable system are first ofall designed on the basis of at least one design criterion. The sum ofthe section lengths, weighted by the cross section of the cable cores inthe sections 12 to 27, is then likewise determined, also in step 56. Thevalue measure is then determined on the basis of this sum. For example,the value measure may be equal to the reciprocal of the sum. The valuemeasure in the present case is thus determined on the basis of thedesign.

[0049] The determined value measures are likewise output via the monitor33 from the computer in a step 57. In this case, they are output inaddition to the display of the topology of the cable system. In thepresent case, the value measures shown in FIG. 1 are indicated directlyabove the respective feed points 40, in the form of vertical bars. Thebar lengths are proportional to the value measure. The value measure isthus output to the user 38 of the configuration tool 37 as a function ofthe feed point 40. The respective value measures are in this caseassociated, in terms of their positions, with the corresponding feedpoints 40 in the output.

[0050] The value measures have different values. The computer thereforecompares the value measures in order to determine the largest or optimumvalue measure. This value measure is emphasized visually in the output.As is shown in FIG. 1, this is done by overlaying an arrow 41. However,other displays would also be feasible, for example by means of a coloredmarking or by blinking.

[0051] In the method proposed in the patent application mentioned aboveentitled “Computer-aided test procedure for a cable system”, the crosssections of the cable cores are limited to a maximum cross section. Whenthe feed module 6 is connected to some feed points 40, it is thuspossible that the design criterion or the design criteria may not besatisfied even if the cable cores in the sections 12 to 27 are of themaximum size. If the aim is to comply with the design criterion or withthe design criteria, feed points 40 such as these are not permissible.These feed points 40 are thus allocated to the value measure 0, andthese areas are marked on the output of the value measures as not beingpermissible. This may be done, for example, by shading as shown inFIG. 1. Alternatively, for example, it would be possible to omit themcompletely or to mark them in a fault color, typically red.

[0052] As is shown in FIG. 5, a step 58 now asks whether the user 38wished in step 54 for the computer to automatically define the finalfeed point. If yes, in a step 59, the computer accepts the feed point 40which has achieved the optimum value measure as the final feed point 40.Otherwise, the final feed point 40 is proposed by the user 38 to thecomputer. To do this, the computer first of all, in a step 60, proposesone of the feed points 40 to the user 38, preferably the feed point 40which has already been determined to be the optimum feed point 40, asthe final feed point 40. A question is then asked in a step 61 as towhether the user 38 has or has not confirmed this proposal. If the user38 has confirmed the proposal, the proposal is accepted in a step 62.Otherwise, in a step 63, the user 38 asks for a position for the finalfeed point 40. The final feed point 40 must in this case lie on thebasic grid. Once the final feed point 40 has been defined, a step 64 iscarried out. In this step 64, the sections of the cable system aredesigned once again on the basis of the design criterion. The procedureis the same as that before in step 56. The topology determined in thisway and its design can then, for example, be printed out on the printer34, or stored in the file 39.

[0053]FIG. 6 now shows a modification of the method shown in FIGS. 4 and5. As is shown in FIG. 6, steps 65 and 66 are inserted between the steps53 and 54. In the step 65, the computer asks the user 38 for a technicalcriterion on the basis of which the value measure will be determinedand, if required, the final feed point 40 will later be defined. In thestep 66, it is possible to enter the part of the cable system in whichthe feed points 40 are intended to be arranged. This allows the user 38to limit the computation complexity from the start.

[0054] The method described above in conjunction with the main cablesystem may be carried out in an analogous manner—with appropriatelyadapted technical and design criteria—for the auxiliary cable systems aswell. The value measures for the auxiliary cable systems are alsopreferably overlaid on the display of the main cable system and itsvalue measure. This is symbolized by further bars 42, 43 in FIG. 1. Thejoint overlaying of all the value measures is in this case particularlyworthwhile because the cable systems may have different loads 1 to 5, 7to 11, 28, 29 to one another, and may thus have different loadstructures. In particular, those areas in which the feed point 40 maynot be arranged may differ considerably from one another. However, ifall the value measures are displayed at the same time it is easilypossible to locate the final feed point 40 such that a permissibledesign can be achieved for all the cable systems.

1. Computer-aided method for configuration of a cable system, via whichat least two electrical loads (1-5) are intended to be capable of beingsupplied with low voltage from at least one feed module (6), with atopology of the cable system being entered in a computer, with the cablesystem having a single section (18-27), corresponding to the topology,per load (1-5), via which only this load (1-5) is intended to be capableof being supplied with electrical power, with the cable system havingconnecting sections (13-17), corresponding to the topology, via whichthe single sections (18-27) are intended to be connected to one anotherand via which it is intended to be possible to supply in each case atleast two of the loads (1-5) with electrical power, with the computerdetermining a number of feed points (40) at which the feed module (6) isintended to be connected to the cable system, with the computerdetermining a value measure for the cable system for each feed point(40) on the basis of at least one technical criterion, and with thevalue measure being output as a function of the feed point (40) to auser (38).
 2. The method as claimed in claim 1, characterized in thatthe cable system is represented graphically by the computer by means ofan output device (33), in that the value measures are likewise outputfrom the computer by means of the output device (33), and in that therespective value measures are associated in terms of their positionswith the corresponding feed points (40) in the output.
 3. The method asclaimed in claim 1 or 2, characterized in that the computer determinesan optimum value measure, and in that the optimum value measure isvisually emphasized in the output.
 4. The method as claimed in claim 1,2 or 3, characterized in that, once the value measure has been output asa function of the feed point (40), a final feed point (40) is defined.5. The method as claimed in claim 4, characterized in that the finalfeed point (40) is defined automatically by the computer.
 6. The methodas claimed in claim 4, characterized in that the final feed point (40)is predetermined by the user (38) for the computer once the valuemeasure has been output as a function of the feed point (40).
 7. Themethod as claimed in claim 6, characterized in that the computerproposes to the user (38) one of the feed points (40) as the final feedpoint (40), and in that the computer adopts this feed point (40) as thefinal feed point (40) if the user (38) enters a confirmation for it. 8.The method as claimed in one of the preceding claims, characterized inthat the sections (12-27) of the cable system are designed on the basisof at least one design criterion, and in that the value measure isdetermined on the basis of the design.
 9. The method as claimed in claim8, characterized in that the value measure is determined on the basis ofthe sum of the section lengths, weighted by the cross section of thecable cores in the sections (12-27).
 10. The method as claimed in claim8 or 9, characterized in that the cross sections of the cable cores arelimited to a maximum cross section, and in that the feed points (40) aremarked as not being permissible if the design criterion is not satisfiedduring connection of the feed module (6) to these feed points (40), evenfor the maximum sizes of the sections (12-27).
 11. The method as claimedin claim 8, 9 or 10 or one of claims 4 to 7, characterized in that,after defining the final feed point (40), the sections (12-27) of thecable system are designed once again on the basis of the designcriterion.
 12. The method as claimed in claim 11, characterized in thatimmediately adjacent feed points (40) are separated from one another byone grid unit.
 13. The method as claimed in claim 12, characterized inthat the grid size is predetermined by the user (38) for the computerbefore the value measures are determined.
 14. The method as claimed inclaim 12 or 13, characterized in that the grid size is an integermultiple of a basic grid, and in that the final feed point (40) lies onthe basic grid.
 15. The method as claimed in claim 14, characterized inthat the basic grid is predetermined by the user (38) for the computer.16. The method as claimed in one of claims 12 to 15, characterized inthat at least one feed point (40) is arranged in each connecting section(13-17), independently of the grid size.
 17. The method as claimed inone of claims 12 to 16, characterized in that at most a predeterminednumber of feed points (40) are arranged in each connecting section(13-17) independently of the grid size.
 18. The method as claimed in oneof the preceding claims, characterized in that the user (38)predetermines for the computer the part of the cable system in which thefeed points (40) are intended to be arranged.
 19. The method as claimedin one of the preceding claims, characterized in that the technicalcriterion is predetermined by the user (38) for the computer.
 20. Themethod as claimed in one of the preceding claims, characterized in thattwo cable systems are entered in the computer at the same time, in thatthe cable systems have at least the feed module (6) in common, and inthat the computer determines a specific value measure for each of thecable systems on the basis of one of the above claims, and this isoutput to the user (38) as a function of the feed point (40).
 21. Themethod as claimed in claim 20, characterized in that at least one of theloads (8, 10, 29) is also common to the cable systems.
 22. The method asclaimed in claim 20, characterized in that an upstream switching andprotection module (7-11) is entered in the computer for at least one ofthe loads (1-5) in one cable system, and in that the switching andprotection module (7-11) is a load on the other cable system.
 23. Themethod as claimed in claim 20, 21 or 22, characterized in that at leastone of the cable systems is assumed to be operated with a DC voltage, inparticular in the DC voltage of 24 V.
 24. The method as claimed in oneof claims 20 to 23, characterized in that at least one of the cablesystems is assumed to be operated with a single-phase AC voltage, inparticular with a single-phase AC voltage of 230 V.
 25. The method asclaimed in one of claims 20 to 24, characterized in that at least one ofthe cable systems is assumed to be operated with a three-phase ACvoltage, in particular with a three-phase AC voltage of 400 V.